1. Field
Exemplary embodiments of the present invention relate to an organic light emitting diode (OLED) display and a manufacturing method thereof.
2. Discussion of the Background
An organic light emitting diode (OLED) display includes two electrodes and an organic emission layer disposed between them, and electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer to generate excitons and light emission is performed while the excitons discharge energy.
In order to apply such an OLED display to a large-sized display such as a TV, the size of the OLED display has been increased, but a large-sized fine metal mask (FMM) for the enlargement of the OLED display cannot be easily manufactured when a thin film is formed through a vacuum deposition process using an FMM. Thus, a method for printing by liquidizing an OLED material has been proposed for application to size-enlargement of the OLED display.
A general printing method includes slit coating, inkjet printing, nozzle printing, and the like. In determining the thickness and a profile of the surface of a thin film using such a printing method, a complex shape of the surface of the thin film in which layers are stacked cannot be easily analyzed, so that discharge amount control in the printing apparatus has been monitored using a weight measuring method, a thin film thickness measuring method, a vision measuring method, a transmittance measuring method, and the like. However, the weight measuring method, the vision measuring method, and the transmittance measuring method cannot acquire information on a unit layer printed to an OLED panel.
In addition, in case of ellipsometry, which is a thin film thickness measuring method used in a vacuum deposition process, a beam size appropriate for the thickness of an organic layer is a unit of millimeters, and therefore, it is not easy to measure a film thickness in a pixel of tens to hundreds of micrometers or to measure a surface profile. Therefore, in order to acquire information about a unit layer, a monitoring pattern area of several millimeters is required at an outer edge of a substrate, and the thickness cannot be determined in real time as a result of a vacuum process so that, if a failure occurs, it may take an undesirably long period of time to address the failure.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and, therefore, it may contain information that does not constitute prior art.